1. Field of the Invention
The present invention relates to a mark position detection device and a mark position detection method, an exposure apparatus using the same, and a device manufacturing method.
2. Description of the Related Art
In semiconductor manufacturing processes, semiconductor exposure apparatuses perform exposure processing for exposing a wafer (substrate) to the circuit pattern formed on a mask. There is a demand for recent semiconductor exposure apparatuses to achieve high performance, such as an overlay accuracy of 5 nm and a throughput of 150 to 200 wafers/hour. Hence, accuracy improvement and processing time reduction are crucial, which leads to an increasing demand for measurement time reduction in wafer alignment measurements.
Japanese Patent Laid-Open No. 2003-92248 discloses a position measurement apparatus that simultaneously images the alignment mark of a wafer viewed by two imaging systems, low magnification and high magnification, so as to reduce the time required for driving the stage. More specifically, the position measurement apparatus simultaneously images the alignment mark by the low magnification imaging system and the high magnification imaging system, and calculates the position of the alignment mark by the low magnification imaging system and the high magnification imaging system, respectively. Then, the shift amount of the alignment mark position is determined on the basis of rough measurement results obtained by the alignment mark image captured at low magnification. As a result of this determination, if the shift amount of the alignment mark captured at low magnification is a shift amount which is applicable to precision measurements, the position information obtained by the image captured by the high magnification imaging system is employed as the precision measurement results.
Here, in the wafer alignment measurement disclosed in Japanese Patent Laid-Open No. 2003-92248, if the shift amount for the position of the alignment mark by rough measurements is a shift amount which is applicable to precision measurements, the driving of the stage for precision measurements becomes unnecessary. However; if the shift amount for the position of the alignment mark by rough measurements is too large to be applicable to precision measurements, driving of the stage needs to be performed so as to execute imaging of the alignment mark by the high magnification imaging system again. Therefore, in such a case, driving of the stage is required, whereby a reduction in measurement time may not be achieved.
In addition, in the aforementioned wafer alignment measurement, if a large-scaled image sensor, which is compatible with a wide range measurement visual field required for rough measurements and a fine resolution required for precision measurements, is employed in the imaging system, the number of pixels of the image sensor is excessively increased. Consequently, the time taken to read out an image from the image sensor becomes longer than the time taken to drive the stage, resulting in no reduction in wafer alignment measurement time.